One type of discrete track media (DTM) structure utilizes a pattern of concentric discrete zones for the recording medium. When data are written to the recoding medium, the discrete magnetic areas correspond to the data tracks. The disk areas not containing the magnetic material isolate the data tracks from one another. The discrete magnetic zones (also known as raised areas, hills, lands, elevations, etc.) are used for storing data and the non-magnetic zones (also known as recessed areas, troughs, valleys, grooves, etc.) provide inter-track isolation to reduce noise. The lands may have a width less than the width of the recording head such that portions of the head extend over the troughs during operation. The lands are sufficiently close to the head to enable the writing of data in the magnetic layer. Therefore, with DTM, data tracks are defined both physically and magnetically.
One conventional way of fabricating DTM is to etch the magnetic layers of current perpendicular magnetic recording (PMR) media to generate the grooves and lands structure. In the etching process, the grooves will lose their magnetic property when the etching removes the magnetic components. The challenge associated with etching the magnetic alloys is that the etching process should be low cost (cost-effective) and fast (high throughput) in order to have cost effective fabrication for commercial applications. Commonly used etching techniques include reactive ion etching, focused ion beam, and ion milling (or sputter). However, these etching methods may suffer from cost inefficiencies due to the high operating costs associated with the requirements of operating inside a vacuum, use of multiple masks and slow throughput.
Electrochemical etching or electroetching has been used widely in the etching of metals in different industries such as optical storage media, printed circuit boards, integrated circuits, and semiconductors. However, electrochemical etching or electroetching method have generally not been used in the fabrication of magnetic recording disks other than for etching of substrates due to problems thought associated with electrochemical etching of layers of a magnetic recording disk. For example, the perceived problems associated with etching perpendicular magnetic alloys using conventional methods are caused by the magnetic composition and structure of the magnetic recording layer. Perpendicular magnetic alloys contain platinum, chromium, and other elements besides cobalt or iron. Metals like platinum and chromium tend to form precipitate under wide range conditions. The electrolytes used in some conventional chemical etching processes contain strong acids or oxidizing agents such as HCl, H2SO4, HNO3 which may be incompatible with magnetic alloys as they may cause corrosion problems and other fabrication problems for DTM disks.